The goal of this project is to develop high quality, low cost, safe, easy to use wheelchair-based exercise machines. The machine will be especially useful for individuals that are not able to get out of a wheelchair on their own. The machine provides continuous passive motions of the legs, arms, and torso, at variable rates. The machine also allows voluntary muscle contractions to be performed simultaneously with passive exercise. Phase I research and development will focus on improving the design and construction of an existing prototype device; to enhance performance, to refine safety features, and to reduce manufacturing costs. Phase II research will concentrate on clinical testing. Sensors will be implemented in order to permit feedback on the levels of muscle activity, and to predict joint reaction forces. The applications of this device for the treatment of orthopaedic injuries and for the rehabilitation of nuero-muscular deficits are broad-ranging.